Don't leave the United States.

That's the advice from high-tech venture capitalist Kate Mitchell, who notes that President Trump's crackdown on foreign entry into the United States may make returning difficult or impossible.

A partner at Silicon Valley's Scale Venture Partners, Mitchell says it's best to play it safe: "Common sense would say, why take the risk?"

More than any other sector of the U.S.economy, Silicon Valley relies upon workers from around the world.Technology start-ups hire the best candidates no matter where they live, counting on the American visa system to allow the new workers to enter the country quickly and start work.

President Trump's travel ban, enabled via an executive order issued last week, temporarily suspends immigration from seven Muslim countries and shuts down the U.S.refugee program for four months.The ban has caused airport delays not just for citizens of those countries, but for anyone who has traveled through the countries.

"Here and now, today, we have businesses that are stopping because their employees can't travel in and out of the United States," said David Cowan, a partner at Silicon Valley firm Bessemer Venture Partners. "This will be the number one cause of missed business plans in 2017."

No one is sure what the travel ban's final terms will be and how they will be enforced, but experts say that it will in any case be a blow to Silicon Valley.Ironically, tech insiders say the ban is likely to slow job growth and spur more firms to locate overseas, outside the U.S.economy, thus throwing a monkey wrench into the Trump administration's economic priorities.